Telephone system.



F. Nl. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION FILED 1AN.3|. |916,

Patented oet. 29, 1918,

- FRANK M. SLQUGH, 0F ELYRIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TOSTROMBERG-CARLSON TELEPHONE MFG. CO., OF ROCHESTER, NEW YORK, A

CORPORATION or NEW YORK.

d TELEPHONE SYSTEM.

nasaece;

Specication of Letters Patent.

Patented Uct. 229, Mlle.

Original application filed November 12, 1914, Serial No. 871,666.Divided and this application filed January 31,1916. Serial No. 75.222.

To all Itti/0m t may concern:

-Be it known that I, `FRANK SLOUGH, a citizen of the United States,residing at Elyria, in the county of Lorain and State of Ohio, haveinvented certain new and useful improvement-s in Telephone Systems; andl do hereby declare the followingto be a full, clear, and exactdescription of thein vention, such as will enable others skilled in theart to which it appertains to make and use the same.

My invention relates to improvements in telephone systems, andespecially to iinproveineiits in what are known as automatic ringing,systems, in which mea-ns `are provided for continuing' the ringing ofthe subscriber, after itlias once been started by the operator, untilthe subscriber responds, ivlien it is automatically disconnected throughagencies under the con-trol of the subscriber. In systems of this kindheretofore in use, so far as I ain aware, the disconnect apparatushasbeen made suchthat it would re spend to the substation signaloperating` current it the conditions happened to be right. For example.in the strength of current systems which are those almost universally inuse, so far as I ain aware, the disconnect apparatus has been operatedby increasing` the tovv of' current in the line, for example, bysubstituting a low resistance talliiigset for Vthe high resistance bellbridge, and thereby increasing' the strength of the current, so

that the disconnect device would operate,. whereas, it had refused torespondto the strength of current flowing` before the low resistancebridge was placed upon the line. lf, however, `connection were inadeto aline upon which were a number `of su'bstations, the impedance offered tothe flow of alterhating` current or signal operating current would be soreduced according; to a Well known law of electricity, that the flow ofcurrent would noiv be sufficient to operate the disconnect device justas elfectivelyas if the subscriber had responded. Therefore, the firstimpulse of ringing current `would i'lisconnect the ringing `currentandthe desired subscriber Would neverbe rung.

ltreonently, alsol` the conditions of a line are such that less currentwillflow over the same when the receiver is off the hook Vthan williioiv over a short line when the reerable limitation has been placedupon the use of the saine, and the operating coinpanics employing thesame have been handicapped, especially where long' country lines andshort city lines center in the saine ,en

change. This trouble has also been keenlyv felt Where multi-party lineshave been cm- Vployed, and as these conditions of long and short lines,some` of which are multi-party lines, are employed in practically allenA changes, the automatic ringing hitherto used has had itslimitations.

Efforts have also been made, so l am informed, to cure vthese defects,one of which has been the employment cfa" specially coustructed relay inthe ringing circuit. @ne of the forms which has been employedfor thispurpose was constructed ivitha copper band around a portion of the core,the copper band being provided `as a sort of closed secondarytransformer Winding for the purpose of dissipating the alternating`current pulsations, the idea beingto cause the rela v to be insensitiveto alternating current tloiv. at the saine tiinebeing sensitive todirect current flow. Such expediente have failed largely because of thefact that such a relay is composed in part of a normally open ina neticcircuit, and is, therefore, inefficient as ai transformer, particularlyto alternating currents of commercial frequencies used for the purposeof ringing telephone bells. Therefor, only a portion of the alternating`current pulsations Would be subdued by the 'copper band, the balancebeing; sometimes` suicient to cause the ope ation of therelay. Suclisystems have. been subject to the same defects heretofore described, inthat sible to exclude all of the ringing` current' and at the same timeenable the subscriber at all times to control the cut-oli device, andil:`

the system 'was so constructed that little or none of the ringing`current, passed through the cut-oll` control arrangement, the conditionswould be such that for certain lines insuliicient current could passthrough to cause its operation. In fact, all oli' the automatic ringingsystems hitherto in use, so far as I am aware, have been quite marginalin one respect or another, and conditions have been such that i'orcertain lines they would open ate improperly, and as such lines arealways met with in practice., sooner or later, these systems have beendetective.

Needless to say, numerous other eli'orts have been made to improve thesystem so as to make it meet all the conditions of practice, but so faras I am aware, this has not been done.

The object of my invention is to overcome these obstacles and toproducea cut-ott device Which vill under no circumstances respend tothe ringingcurrent at all until the subscriber has responded. In aeconr plishing`these, I wipe out all oit the delicate adjustments, strength of current,marginal Schemes, mechanisms for preventing the cutoii controllingapparatus from responding to fluctuating; currents and other suchdelicatemechanisms, and provide a cutbll controlling mechanism whichresponds to the alternating current or not. My success lies in providinga cut-off mechanism which will not respond, even though its controllingmechanism is responsive to fluctuating currents. I further provide meanscontrolled by the subscriber1 for causingthe operation of the cut-oiimechanism and a cut-oil." mechanism which will notl respond until thesubscriber starts the same into operation.

@ther objects of my invention and the invention itself Will probably bebetter understood from a description of particular embodiments.

This application is a division of my application #871,666, filedNovember 1914i. Figure l is an illustration of the preferred embodimentof my invention.

Fig. 2 is a diagrammatic illustration ot' electric current and magneticilus; Waves.

Referring non7 to the embodiment illustrated in Fig. l, at I is shown atelephone line which may be here spoken of properly as thc calling line,and which I have ior convenience shown as a single partyelii'ic. At II`is shown a. second telephone line, shown lor convenience as amultieparty line, and which may be properly called a called line. At IIIis shown a main station. Each telephone line is provided With substationapparatus, shown on the line ^I n and which includes a signal bell B, areceiver l, a transmitter D and a switch-hook E. A condenser 6 may beincluded in the bell bridge 7. The line I is connected by lineconductors 8 and 9 to the main station. The line II is provided With aplurality of substations, A1, A2, A3, A4. VEach is provided with bellsB1, Bg, B3, 13 which are included in the telephone apparatus. Thisapparatus also includes receivers C1, C2, C3, C4, transmitters D1, D2,DE, D and switch hooks El, E2, E3, E4. Condensers may likewise beconnected in the bell bridges.

I have illust ated a third telephone line,

shown at IV, which may also be called a called line. This line isprovided with substation apparatus A5 which includes a. bell B5, areceiver C5, a transmitter D5 and switclrhoolc E5. The line II leads byits line limbs or conductors 1G and l1 to the main station and the lineIV leads by its line limbs or conductors 13 and 14 to the main station.At the main station means are provided for connecting the telephonelines together, here shown as a cord circuit, `which consists of aplurality of strands in cluding talking strands l5 and 16. Switchingapparatus is provided for connecting the cord circuit to the telephonelines, here shown as plugs and jacks, the line I beingv provided with ajackl, the line II vwith jacks J, and J2 and the line IV withV jacks Jand Ji. The cord is provided with a n answering plug I and a callingplug Ill. l? course the lines may be provided with any suitable numberof jacks. Each line is also provided with line signals, the line I Withthcline signal L1, the line II with the line signal L2 and the. line IVwith the line signal L4. Each line is also provided with line relays,the line I with the line relay Gil, the line II with the line relay G2and the line IV with the line relay Gp Each line is also provided withcut-oli0 relays, the lines I, II and IV being provided with the cut-oli'relays H1, H2 and IL, respectively. The cord circuit is provided Withsuitable supervisory signaling appad ratus, the answering end of thecord being provided with a supervisory lamp L and the calling end of thecord being provided with a supervisory lamp LG. These lamps arecontrolled by supervifscry relays K, Kl for the lamp L Vand Iig and IL,'l'or the lamp L6.

IIO

Means are provided for operating the Signal tens B, B1, B2, B3, B B5. inthe Vform shown these means are located at the scriber is connected, butone generator is necessary. In this vwell known harmonic system eachgenerator is adapted to produce an alternating current of a certaindefinite frequency and the bells at the substations respond one to eachof these frequencies. This arrangement, however, may be employed withoutdeparting from the spirit of my invention.` Means are provided forconnecting one of the generators to the bell of the desired subscriber,in order that the bell may be operated by the current supplied by thegenerator. In the form shown, this connection is effected throughconductors, switches, a portion of the cord circuit, the apparatus forconnecting the cord to the lines and the telephone line. In the formshown I provide means for breaking up the ringing current intointervals, so that the subscribers bell may be rung at intervals,avoiding an incessant ringing of the bell. These means are shown ascommutatore N,

N1, N2, N3 which rotate constantly alternately making and breaking thecircuit of the ringing circuit. At O, O1, shown switches, hereillustrated as manual switches controlling the connection of thegenerating means to the signal bell, one key being provided for e-achgenerator.

At Q, Q1, Q2 and Q3 I show relays which are controlled by the keys O,01,02, O3,

which in turn control the connection of the generators to the lines. AtRis shown a relay which controls the talking strands of the cord circuitand the connection of the ringing current to the telephone line. At S isshown a relay which controls the disconnection of the ringing currentfrom the telephone line. This relay also controls the circuits of therelays Q, Q1, Q2 and Q3. While the ringing is in progress, ringingcurrent flows through the relay S, but the current produced by thegenerating means is of such a character that the armature of the relay Sfluctuates without closing the switch -21 for any appreciable length oftime, so that the connection `between the ringing generator and the bellwill not be interrupted. When, however, the character of the currentflowing through the relay S is so changed that the magnet luX isconstant or substantially unidirectional, the

O2, O3 are switch 20`-2l is closed and whichever one of the relays Q,Q1, Q2 or Q3 has been operated, will be denergized and the connectionbetween the ringing generator and the bell interrupted. The character ofthe current which flows through the relay S may be changed in a numberof ways and the character of the flux in the relay S may be changed in anumber of ways to effect the functions which it is to perform. In thcform shown I have accomplished this change by superposing upon thealternating current produced by the generator a directw current, which,upon the response of the called subscriber, will cause a result-antcurrent of a dierent character. In the embodiment illustrated in Fig. lthe wave form will be .changed with respect to the line of zeropolarity. llhile lthe unmodified alternating current was flowing, theflux in the circuit of the relay S would be of alternating polarity,following the alternating current.

However, when the current is shifted, its flux will be substantiallyconstant, or of substantially uni-directional polarity, and the magnetwill be operated for a sutlieient length of time to cause thedisconnection. However, when the alternating current alone is applied,the switch 20-21 will be closed for such brief intervals of time thatthe magnet Q will never let go its contacts.

The operation of the system illustrated in Fig. l as follows: Assumingthat the sulscriber at A desires to communicate with the subscriber atA5, the receiver C is removed from the switch-hook E. closing the switchIlk) and completing a circuit through the` line relay G1, causing' theillumination oi the line lamp L1. This lamp is located sn that it willattract the attention of the operator, who will insert the plug P intothe "ack J and in the well known manner learn that it is the subscriberat A that is wanted. She then inserts the plug l), into one of the`jacks J, and deprcsses one of the ringing keys, according to whatcharacter of current is desired. Assuming that the generator .ll/lproduces the character of current desired. the key 0 would be depressed,completing a circuit as follows: ground at QS-contact 24-OrelayQ-conductor 25-relay R- conductor 26-27-2S-29-30-312w33 S4- battery35-to ground at 3G, energizing the relays Q and R, the relay K havingpreviously been energized in the well known way when t-he plug P wasinserted into the jack H through a circuit. including the answering endof the cord and the calling line. and atl, completing a locking circuitfor the relay Q through LO Y i2 to ground at 4&3. The attraction of thearmature Ll1 closes a switch iL-eli in the ringing circuit. The relay Rattracts its armatures l5 and 46, in-

terrupting the talking strands of the cord The relay Q will attract itsarmatures circuit and closing the switches t5-47 and i6-i8 in theringing cir-cuit. The ringing circuit vvillxnoiv be traced as follows:from ground Jew-through Mconductor Ocon mutator N-conductorT-TJfJr-tl-relay S -Q-fllT-et-tip i3-tip spring .5t-conductor li-thebell Il conductor 13 lea'f spring -sleeve 5(5-iG-,`LS-batteiy G0-` toground (Si. Thus current Vtlowiiig through the relay S will rapidlyenergize and denergize the saine in such a manner that the switch 20-21will be closed, if at all,ronly for short intervals of time. The periodsfor which this switch will be closed, ii at all, will be functional tothe frequency or' and in harmony with the ringing current employed. Theintervals of closure of this switch during the ringing period will besoslight that the shunting effect of the magnet Q will be ineffective todenergize the relay Q, owing to the fact that the magnetism in ashort-circuited relay decays very sloivly. All during the ringingperiod, the condenser 62 at sub- Vstation A5 preventsthe flow o't directcurrent from the battery 60.

Vhen the subscriber responds, the switch Fir-G3 will be closed, oivingto the removal of the receiver C5 from the hook E5, which maybe springpressed upward. V This vvill shunt the condenser 62 and admit the lovvot' direct current from the source 60. As a rcsult, a different kind otcurrent will flow in the circuit, including a relay'S, and as a resultthereof the relay S will operate. In the #form shown the current ioivingin the cir Acuit of the relay S, atterthe receiver is removed from thehook, will be an alternating current, which is shifted with respect tothe zero abscissa, or it may be a pulsating current, according to therelative strength of the alternating` and direct currents. This currentwill cause a substantially constant, or substantially unidirectional,flux to tlovv in the magnet S. The magnet of the relay S will now beenergized for a sufficient length of time to hold steadily closed thesivitch Z0-2l long enough to effectively shunt the magnet Q which Willbe denergized, Where upon the armature 41 drops back, opening theringing circuit at 41-44: and disconnecting the generator from thesignalbell. At the saine time, the circuit of the relay t will be broken,still further interrupting the ringing circuit and restoring the cordcircuit; The subscribers Will then be in connection and at thetermination of the conversation, the operator will be apprised of thedesire for the disconnect, and the plugs will be Withdrawn, restoringthe system vto normal.A

In Fig. 2 I have shown diagrammatieally one theory upon which myapparatus may be operated. `The curve X represents the flow ot'alternating current during the ringing period. The curve Y representsthe direct current introduced :into the circuit when the receiver istaken from the hook. The curve Z representsthe polarized alternatingcurrent inthe ringing circuit When both the ringing machine and thesource are connected to the ringing current. VThe curve IV representstlieiiux in the relay S when both the ringing machine and the directcurrent are connectedin the circuit.

. I have shown the `theoretical diagram illustrated in F 2 as being amere theory as toivliat might take place under a given set ofconditions, but I do not Wish to be limited either to the embodimentillustrated in Fig. 1 or to the theory of operation Which I haveillustrated in Fig. In fact, .I have illustrated `this embodiment andthisA theoretical diagram in order to better explain `my invention, andnot, that I `may kbe limited thereto, as it -ivill be apparent that manyi departures may be made from the modifications and the theoryillustrated, especially *when the claims are consulted.

vand means controlled bythe substation apparatus tocause said secondrelay to close the contacts in the circuit ofthe iirst named relay toran appreciable length `of time,

whereby said relay is operated to interrupt the ringing circuit. Y y

2. In a telephonev syst-ein, thej combination oi Va signalY device, asource or" current, a ringing circuit including said source andsaidsignal device, a relay controlling said `ringing circuit, a circuitfor said relay, a

shunt et said relay and a second relay in the ringing circuitcontrolling said shunt,

a shunt ot the second relay and a non-iiiductive resistance in saidshunt and substation apparatus associated with the signal devicecontrolling said second relay.

3. In a telephone system, the combination of a main station, a telephoneline leading to the main station, substation apparatus on the lineincluding a signal bell and a switch, means at the main station forgenerating current to operate the bell, a ringing circuit including saidbell and said generating means, a relay for the ringingcircuitcontrolling the same, a second relay in the ringing circuitgoverningV said firstnained relay, i a. shunt `oi thev second relay anda non-inductive resistance in said shunt and means including the switchat the substation controlling the slo7 acting relay.

4. In a telephone system, the combination of a signal device, a sourceof alternating ringing current, a ringing circuit including said sourceand signal device, a relay oontrolling said ringing circuit, a oil-Cuitfor said relay, a shunt of said relay, a second relay responsive to aflow of polarized ourrent to Control said shunt to shunt said rstnamedrelay, said second relay being irresponsive to alternating currents tocause the operation or' the first relay, a shunt of the second relay anda non-inductive resistance in said shunt and substation apparatusassociated with the signal device adapted to cause a flow of polarizedcurrent through said second relay to operate the second relay.

In witness whereof I have signed my name hereunto this 22nd day ofJanuary,

FRANK M. SLOUGH.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

